Dynamoelectric machine



1945- N. J. GREENE ET AL DYNAMOELECTRIC MACHINE Filed April 27, 1943 INVENTOR Nathan J. Greene Michael Liwschi GariK ATTORNEY Patented Feb. 27, 1945 DYNAMOELEGTRIC MACHINE Nathan J. Greene, Columbus, Ohio, and Michael Liwschitz-Garik, Brooklyn, N. Y., assignors to National Electric Coil Company,

Columbus,

Ohio, a corporation of West Virginia Application April 27, 1943, Serial No. 484,730 18 Claims. (o1; 171-2os) The present invention is directed to electric machines and more specifically to the armature coils for alternating or direct current machines.

One of the objects of the present invention is to provide a slit or slits extending longitudinally of the bar to divide the latter into radially superimposed sections, when disposed in the slots of the armature core.

In carrying out the above object, it is another object of the invention to interpose insulating material within the slits and along the sides of the bar for insulating the sections of the bar from one another.

Another object of the invention is to extend the slit or slits and the insulation therefor beyond the opposite sides of the armature core.

Another object of the present invention is to utilize a single strip of insulating material for insulating sections of a single bar from one another, and for insulating certain opposite sides of the section from the next adjacent bar or bars and this is accomplished by threading the insulating material through the slit bar and disposing the sections of the material, which extends beyond the slit along opposite side portions of the bar.

I Another object of the invention is to thread an insulating strip through the slit in the bar and dispose one of the extending sections of the strip alongone side of one of the bar sections and dispose another extending section of the strip along the opposite side of another of the bar sections.

Further objects and advantages will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred form of one embodiment of the present invention is clearly disclosed.

In the drawing:

Fig. 1 is a perspective view of a single armature bar with slits therein, a portion of the insulation disposed in the slits also being shown;

Fig. 2 is a. perspective view of three similar contiguously placed armature bars, said view also showing a portion of the insulating material;

Fig. 3 is a sectional view on a large scale, the section being taken on line 3-3 of Fig. 1, and showing the continuous strip of insulation provided within the slits of the armature bar;

, Fig. 4 is a sectional view taken on line 4-4 of Fig. 2, but on a large scale, and showing a fragmentary part of an armature core;

Fig. 5 is a perspective view showing an electric coil made up of two armature bars or half-turn coils, and showing an end of one bar connected with an end of the other; and, I

Fig. 6 is a perspective view of two series of three bars and showing a connecting clip for the series fastened to the bars of one of the series; and,

Fig. 7 is a side view of an armature, said view being partly fragmentary showing the armature bars in actual position and being partly diagrammatic to show the outlines of the armature.

In the drawing, 20 represents a part of a winding of an electric machine, namely, a narrow rectangular armature bar of electroconductive metal, preferably copper. The armature bar 20, as shown in Fig. 1,-is known as a half turncoil. To reduce the presence of undesirable eddy currents, which cause non-desirable heating and other losses, the bar 20, except the ends thereof is divided into sections which, when disposed in the slot oi an armature are radially superimposed. The bar may be divided into two or more sections and in the present disclosure, the bar is divided into three sections, 2|, 22 and 23. This division is brought about by slitting the bar as shown at 24 and 25. These slits are in parallel relation to each other and extend longitudinally of the armature bar 20. Theslits 24 and 25 are placed so that the sections 2|, 22 and 23 are equal in width. I

A strip of insulating material 26 is provided to insulate the strips 2|, 22 and 23 from each other. The insulation 26 is continuous and extends, for example as viewed in Fig. 3, along the left side of the strip 2 I, through the slit 24, along the right side of strip 22, through the slit 25 and along the left side of strip 23.

The insulation used may consist of mica or any other suitable insulating material which will maintain its mechanical and dielectric strength athigh temperatures, as for example, a copper oxide film, a varnish coated glass tape, etc.

The armature bar 20 has a clip end 27 onwhich is placed a clip 28. The clip shown in the immediate case comprises a thin sheet of copper bent around the bottom and sides of the end 21 of the armature bar 20 and extends beyond the top of the armature bar suiilciently to provide for the mating half turn coil or bar. The clip 28 is attached to the armature bar 20 on the clip end 21 in any suitable manner, preferably by soldering. The other end 29 of the armature bar is known as the commutator end.

One or a series of bars 20 are placed in a slot.

.Figs. 2 and 4 show a series of three bars in side by side relation and Fig. 4 shows the bars in an armature slot 30 of an armature core 3|. Fi 6 shows a series of clips 28 fastened to the ends 2'! of a series of bars and shows the ends 21 of a complementary series of bars 20 which are to be inserted between the clips 28.

Fig. 5 shows two half turns or bars 20, one end of each being joined at 21 by a clip 28 to form a coil 33. Each half turn, whether it comprises a single bar or a series of bars is wrapped with suitable insulating material 34, and this material extends to adjacent the ends 21 and 29. This material 34 is shown in Figs. 4 and 6, but has been omitted in the other figures so as to clearly show the slits 24 and 25. The open ends 29 of the coil are connected to the proper commutator segment connectors 35 of the commutator 36,1an armature 38 including the core 3|, commutator segment connectors 35 and commutator 36 is shown partly diagrammatically in Fig. 7. It will be understood that the slots 30 of the core 3| are the usual type which are circumferentially spaced and radially disposed and extend along the axis of the core.

All of the parts between A and B of each section 2|, 22 and 23 are'disposed in a slot 30 of the core and it has been found that the least amount of heat 'is generated and the highest electrical efficiency is obtained by extending the slits-24 and 25 and the=insulation 26 to adjacent the ends of the bars-"and, in-actual'practice one-half, that is, the central hal'fof the-slitted part of the bar is'containedwithin a slot 30 and the end'quarters'extend from opposite sidesof the slot.

By virtue of the construction herein disclosed,

eddy currents in the coils have been reducedto a minimumwith-the consequent decrease ofh'eating and-increaseofeificiency of the electri'c'machine.

While the formof embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfc'llow:

We claim:

'1. An electric machine, including a rotating armature having "a corewith a plurality of 'circumferentially spaced, radially disposed slots therein,-said slots extending-along the longitu-.

tending slit provided therein.

2. An electric machine, including a rotating armature having a core with a plurality of circumferentially spaced, radially disposed slots therein, said slots extending along the axis of said armature core, a part of a coil disposed in 'eachrslot comprising an elongated strip-like'bar made of a metallic conductor and having unbroken substantially parallel side edges, said bar having'at least'one longitudinally extendingslit formed therein, each slit having a length greater than the length of the "slotin said armature.

3. An electric "machine, including a rotating armature having a "core with a plurality of circumferentially spaced, radially disposed slots therein, said slots extending along the axis of said armature core, a part of a coil disposed in each slot comprisinga bar made of a metallic conductor, said bar having at least one longitudinally extending slit provided therein, said slit having a lengthequal to substantially twice the' length of said armature core.

4. An electric machine, including, a rotating armature having a core with a plurality of circumferentially spaced, radially disposed slots therein, said slots extending along the axis of said armature core, a part of a coil disposed in each slot comprising a strip-like bar having substantially straight sides and being made of a. metallic conductor, said barhavlng a plurality of 1ongitudinally extending substantially traight slits provided therein, said slits extending an equal distance linearly of said bar beyond the confines of said armature core.

5. An electric machine, including a rotating armature having a core with a plurality of circumferentially spaced, radially disposed slots therein, said slots extending along the longitudinal axis of said armature core, a part of a coil disposed in each slot comprising a strip-like conductor with substantially straight side edges having at least one longitudinally extending slit formed therein, said slit having an insulating strip disposed therein to divide the bar into at least two individual conductors having equal cross sectional areas.

6. An electric machine, including a rotating armature havin a core with :a pluralit of pitcumferentially spaced, radially disposed slots therein, said slots extending along the axis :of "said-armature'core, apart of a coil disposed in each slot comprisin a plurality :of adjacent conductor bars, eacl'rof saidIbarsbeingsubstantially as wide .as the depth of said'slots and having at least one longitudinally extending slit provided therein, said slits being substantially parallel to the bottoms of said slots throughout the full length thereof.

7. An electric machine, including a rotating armature having a core with a plurality of circumferentially spaced, radially disposed 'slots therein, said slots extending along the axis of said armature core, a part of a .coil disposed in each slot comprising-one or more adjacent striplike conductor bars, said bars each having one or more longitudinally extending slits formed therein, each of said slits of any one bar in said mentioned slot being in parallel alignment with each of the slits of the adjacent bar, said :slits being substantially parallel to the bottoms of the slots throughout the full length thereof.

8. An electric machine, including a rotating armature having a core with a pluralit 'of .circumferentially spaced, radially disposed slots therein, said slots extending along the :axis of said armature core, a part of a .coil disposed in each slot comprising oneor more adjacent conductor bars, said bars each having a plurality of longitudinally extending slits therein, each-of said slits of any one bar in said slot being in parallel alignment with each of the slits of the adjacent .bar, anda continuous insulating strip extending through the-slits of each bar in each slot.

9. In an armature core for an electric machine, a coil comprising a strip-like conductor .bar'having substantially straight side edges partially embedded'in said armature core, saidconductor bar having at least .one longitudinally extending substantially straight slit therein which is confined between the ends of said conductor bar.

10. In an armature for an electric machine, an armature core, a coil comprising a strip like conductor bar havingsubstantially straight side edges partially embedded in said armature core, said conductor "bar 'being slit to provide longitudinally extending sections "having substantial-1y l We uniform cross sectional areas throughout their length, said sections projecting beyond the ends of said armature core.

11. An armature coil for an electric machine comprising, in combination, a pair of strip-like conductors bent to provide spaced parallel portions and converging ends, each of said conductors having substantially straight side edges and being slit longitudinally to form a plurality of sections, the slits terminating in spaced relation from the ends of said conductors; and means for connecting said conductors at one pair of converging ends.

12. An armature coil for an electric machine comprising, in combination, a pair of strip-like conductors bent to provide spaced parallel portions and converging ends, each of said conductors having substantially straight side edges and being slit longitudinall to form a plurality of sections, the slits terminating in spaced relation from the ends of said conductors.

13. In an armature for an electric machine, a strip-like bar having substantially straight side edges, said strip being slit longitudinally to form a plurality of sections; and a strip of insulating material extending through the slits and along opposite sides of adjacent sections.

14. An armature for an electric machine comprising, in combination, a core having a longitudinally extending slot; a plurality of strip-like bars having substantially straight side edges disposed on edge in said slot, the width of said bars being substantially equal to the depth of said slot; said bars being slit longitudinally to form a plurality of section; and a strip of insulating material extending through the slits in each bar and along opposite sides of adjacent sections to insulate said sections and said bars from one the slits and along opposite sides of adjacent sections to insulate the sections and adjacent conductors from one another.

16. An armature coil for an electric machine comprising in combination, a plurality of pairs of strip-like conductors, each pair being bent to provide spaced parallel core receiving portions and converging ends, corresponding conductors of the pairs being grouped in adjoining relation, each of said conductors having substantially straight side edges and longitudinally extending slits parallel thereto, said slits dividing each of said conductors into a plurality of sections, integrally united at the ends of the conductor; a strip of insulating material extending through the slits and along opposite sides of adjacent sections to insulate the sections and adjacent conductors from one another, and a covering of insulating material surrounding each group of conductors.

17. An armature coil for an electric machine comprising, in combination, a plurality of pairs of strip-like conductors, each pair being bent to provide spaced parallel core receiving portions and converging ends, corresponding conductors of the pairs being grouped in adjoining relation, each of said conductors having substantially straight side edges and longitudinally extending slits parallel thereto, said slits dividing each of said conductors into a plurality of sections integrally united at the ends of the conductor; a strip of insulating material extending through the slits and alongopposite sides of adjacent sections to insulate the sections and adjacent conductors from one another; a covering of insulating material surrounding each group of conductors; and means for electrically connecting ,each pair of conductors in said-groups at one pair of converging ends.

18. An armature coil for an electric machine comprising substantially straight strip-like conductor portions oppositely bent to provide spaced parallel lengths with converging ends, one pair of said ends being united for the passage of electricity, said portions being slit longitudinally to form separate sections integrally united adjacent the converging ends, said slits being straight and substantially parallel to the side edges of said conductor portions.

NATHAN J. GREENE. MICHAEL LIWSCHITZ-GARIK. 

